Remove unused t/t8005/iso8859-5.txt

This file is no longer used since 54bc13ce (t8005: Nobody writes Russian in
shift_jis, 2009-06-18).
Signed-off-by: NNanako Shiraishi <nanako3@lavabit.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

t/t8005/iso8859-5.txt

-ISO8859_5_NAME="  "
-ISO8859_5_MSG=" "